1. Field of the Invention
This invention relates to a method of printing an image of letters, figures, or the like on a plate-making surface of a plate-making sheet in the form of a strip, and an apparatus therefor.
2. Prior Art
Conventionally, there has been proposed a printing apparatus for printing an image of letters, figures or the like on a plate-making surface of a continuous plate-making sheet. The continuous plate-making sheet, which is contained in a cassette as a roll, is set in the printing apparatus, and rolled out for being printed with desired letters, figures, etc. by a print head of the apparatus. A printed portion of the plate-making sheet including a margin thereof is cut off from the remainder. The plate-making sheet is a laminate of a front-side sheet and a reverse-side sheet attached to the front-side sheet. A front-side sheet portion of the plate-making sheet is peeled off a reverse-side sheet portion of the same. The front-side sheet portion printed with the image of letters, figures, etc. is affixed to a place where the image is needed, by the use of an adhesive provided on the underside thereof.
When the continuous plate-mating sheet contained in a cassette as a roll is used, the user simply sets the cassette in position within the printing apparatus, before he starts entering desired letters for plate-making. When a plate-making sheet in the form of a strip is used, however, it is required first to discriminate between a right side (front side) and a wrong side (underside) of the plate-making sheet, and then to print an image at a predetermined location thereon. However, if these works are delegated to the user, there is a fear of errors, and the works themselves are troublesome. Further, this type of plate-making sheet is inconvenient to handle unless it can be fed using either end as a forward end for printing. It is also required that when a plate-making sheet of a quite different or non-conforming type has been inserted erroneously, the apparatus should detect the insertion of such an unsuitable plate-making sheet immediately, and make the user aware of the abnormality to permit him to deal with the abnormality promptly.
Finally, these requirements should be met without undesirably increasing the size of the apparatus, or decreasing the size of the same at the cost of reliability of operation thereof.